JP2009192566A - Optical sub-assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sub-assembly (OSA) which is configured by attaching a sleeve member to an optical module using a cap shell formed by press-molding by an adhesive and can secure a large adhesion area. <P>SOLUTION: The OSA 1 includes a coaxial optical module 20 where a cap shell 23b which holds a condenser lens 23a and is formed by press-molding is attached to a stem 22 on which a PD 21 is mounted, and a sleeve member 10 for arraying the ferrule 51 of an optical connector 50. An extending part 40 extending above the holding surface 23c of the lens 23a of the cap shell 23b is disposed in the cylindrical outer peripheral part of the cap shell 23b, and a recess 12a is formed in the sleeve member 10 to house the cap shell 23b. The outer peripheral surface of the optical module 20 including the outer peripheral surface of the extending part 40 disposed in the cap shell 23b and the inner peripheral surface of the recess 12a of the sleeve member 10 are fixed together by an adhesive. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical subassembly for coupling a photoelectric conversion element of an optical module and an optical fiber of a ferrule of an optical connector received by a sleeve member.

  Some optical modules have a coaxial CAN package in which a lens cap in which a lens is fixed to a cap shell is attached to a stem on which a photoelectric conversion element is mounted. In an optical sub-assembly (OSA) in which this optical module is attached to a receptacle sleeve (sleeve member) for receiving an optical connector, the optical module and the sleeve member are usually fixed by YAG welding. ing. However, when the OSA is assembled by fixing by YAG welding, for example, the OSA production cost is high for the following reasons (1) to (3).

(1) In order to fix by YAG welding as described above, it is necessary to accurately manufacture the fixing portion of the sleeve member and the fixing portion of the optical module (for example, the cap shell constituting the optical module package) by cutting. However, cutting is expensive and difficult to reduce.
(2) For parts fixed by YAG welding, such as cap shells, the material is limited to SUS materials excellent in weldability and machinability, such as ferrite-based SF20T or austenitic SUS303, and more. Inexpensive materials cannot be used.
(3) Equipment required for assembling by YAG welding (YAG light source: 5 to 10 million yen) is very expensive.

Therefore, in order to realize a lower cost OSA, a technique has been proposed in which the optical module and the sleeve member are bonded and fixed by an adhesive such as a resin adhesive instead of YAG welding at the time of assembly. (For example, refer to Patent Document 1). This technology was initially used only for OSAs with a low required assembly tolerance, such as applications using multimode fibers and receiving optical sub-assemblies (ROSA). The use of sub-assemblies (TOSA: Transmitting Optical Sub-Assembly) is gradually expanding.
JP-A-8-129118

  In OSA, in general, in a practical use state, there is a possibility that stress is constantly applied to the fixed portion due to a relative positional shift between the sleeve portion and the circuit board to which the OSA is attached. Therefore, the OSA as a product is required to stably satisfy not only the initial characteristics but also a sufficient fixing strength and a predetermined reliability test. The predetermined reliability test includes, for example, a high-temperature energization test, a low-temperature storage test, a high-temperature and high-humidity test, a heat cycle test, and the like. Reliability that conforms to (Telcordia GR-468-CORE) is required.

  In OSA, when using adhesive fixing for cost reduction, sufficient (high) fixing strength, that is, sufficient (wide) bonding area is required to satisfy the above-described reliability. In OSA, one end of the optical module is inserted into the concave portion of the sleeve member that houses the optical module, and the outer peripheral surface of the optical module and the inner peripheral surface of the concave portion of the sleeve member are bonded and fixed. The adhesion area between the sleeve and the inner peripheral surface of the concave portion of the sleeve member is important.

As shown in FIG. 3, a coaxial OSA optical module is generally formed by attaching a cap shell 112 provided with a condensing lens 111 to a stem 113 on a disk.
In the conventional optical module 110 shown in FIG. 3, when the cap shell 112 is formed by cutting SUS or the like as in the case of YAG welding, the shape can be designed relatively freely. The height of the cap shell 101 can be increased. Accordingly, in the conventional OSA 100 in which the cap shell 112 is manufactured by cutting, the height of the side surface of the optical module 110 is increased, and the space between the side surface of the optical module 110 and the inner peripheral surface of the recess 121 of the sleeve member 120 is increased. It is possible to secure a wide bonding area. However, as described above, this method is expensive.

  When the cap shell is formed by press forming instead of forming by cutting, the manufacturing cost of OSA can be reduced. However, the optical module in this case is generally a flat package in which the lens is stopped, that is, the center of the lens is the height of the cap shell.

  In TOSA using ROSA or a surface emitting laser (VCSEL: Vertical Cavity Surface Emitting LASER), as shown in FIG. 4, the photo is directly applied to the mounting surface 211a of the stem 211 of the optical module 10 (or via a low submount). A chip 212 such as a diode (PD: Photo Diode) or a VCSEL is mounted. Therefore, in the TOSA using ROSA or VCSEL, when the cap shell 213 is formed by press molding as described above and a flat package in which the center of the lens 214 is the height of the cap shell 213 is used, the position of the chip 212 is obtained. In addition, the height of the cap shell 213 is inevitably small as a result of the lower position of the lens 214. For this reason, the area of the side surface of the optical module 21 to be bonded and fixed is small, and the bonding area cannot be increased.

  In particular, in order to increase the coupling efficiency in recent years, a spherical lens having a higher refractive index may be used so as to reduce the spherical aberration. When a high refractive index spherical lens is used, if the cap shell 213 is formed by press molding and the package is formed flat as described above, it is necessary to reduce the height of the cap shell 213 and lower the position of the spherical lens. Therefore, a wide bonding area cannot be secured.

  The present invention has been made in view of the above-described circumstances, and is formed by attaching a sleeve member to an optical module using a cap shell formed by press molding, and ensures a wide bonding area. It is an object to provide an optical subassembly capable of

  An optical subassembly according to the present invention includes a coaxial optical module in which a cap shell formed by press processing for holding a condensing lens is mounted on a stem on which a photoelectric conversion element is mounted, and a sleeve for aligning a ferrule of an optical connector And a cylindrical outer peripheral portion of the cap shell is provided with an extending portion that extends upward from the lens holding surface of the cap shell, and the sleeve member is formed with a recess for storing the cap shell. The outer peripheral surface of the coaxial optical module including the outer peripheral surface of the extending portion provided in the cap shell and the inner peripheral surface of the concave portion of the sleeve member are fixed with an adhesive.

  The extending part is preferably formed by folding the upper outer periphery of the cap shell, and the extending part is a cylindrical shape having an axial dimension larger than the height of the cap shell at the outer peripheral part of the cap shell. It is also preferable that the member is formed by fitting and fixing.

  According to the present invention, in an optical subassembly, an optical module having an inexpensive cap shell formed by press molding and a sleeve member can be fixed using an adhesive, so that the manufacturing cost can be suppressed. Also in this case, an extending portion that extends above the lens holding surface of the cap shell is provided on the outer periphery of the cap shell, and the outer peripheral surface of the optical module including the outer peripheral surface of the extending portion, the sleeve member, Therefore, it is possible to secure a wide bonding area and to give the optical subassembly a high fixing strength.

  FIG. 1 is a cross-sectional view illustrating an optical subassembly (OSA) according to an embodiment of the present invention. As shown in the figure, the OSA according to the present embodiment includes, as an adhesive, a sleeve portion 10 for guiding a ferrule 51 of an optical connector 50 and an optical module 20 having a photoelectric conversion element 21 having a photoelectric conversion function in a CAN package. The adhesive resin 30 is bonded and fixed. The photoelectric conversion element 21 includes a PD that converts an optical signal from the optical fiber 51a in the ferrule 51 into an electric signal, a VCSEL that converts an optical signal to the optical fiber 51a from an electric signal, and the like. The element is assumed to be PD and will be described as PD21.

  First, the sleeve portion 10 will be described. The sleeve portion 10 is formed by, for example, resin injection molding, and a ferrule 51 containing an optical fiber 51a that transmits an optical signal to the PD 21 is inserted. The sleeve portion 10 includes a ferrule receiving portion 11 that receives and guides the ferrule 51 of the optical connector, and a module receiving portion 12 that receives the optical module 20 sealing the PD 21.

  The ferrule receiving portion 11 has a cylindrical portion 11a formed in a cylindrical shape having an inner diameter substantially the same as the outer diameter of the columnar ferrule 51 so that the ferrule 51 can be guided, and at one end thereof In order to facilitate the insertion of the ferrule 51, a tapered opening 11b is formed. Further, an optical member (fiber stub) 11c is press-fitted into the cylindrical portion 11a, and when insertion of the ferrule 51 into the ferrule receiving portion 11 is completed, a spring (not shown) inside the optical connector 50 Due to this elastic force, the optical fiber 51a and the fiber stub 11c are physically in contact with each other. Note that the end surface of the fiber stub 11c on the optical module 20 side is obliquely polished so that reflected return light can be suppressed.

  The module receiving part 12 has a concave part 12a having a shape corresponding to the outer peripheral surface of the optical module 20 on the extension part side so that the extension part side (to be described later) of the optical module 20 can be received. The module receiving portion 12 in the example of FIG. 1 has a concave portion 12a having a shape corresponding to the cap shell 23b of the lens cap 23 so that a later-described lens cap 23 side of the optical module 20 can be received. Further, in the example shown in the figure, the optical module 20 is inserted from the cap shell 23b side with the adhesive resin 30 applied to the inner peripheral surface of the recess 12a of the module receiving portion 12, and the outer peripheral surface of the optical module 20 and the module receiving portion are received. The optical module 20 can be fixed to the sleeve portion 10 by adhering the adhesive resin 30 to the inner peripheral surface of the recess 12a of the storage portion 12 and then solidifying the adhesive resin 30. As the adhesive resin 30, a thermosetting resin can be used.

The sleeve portion 10 has a partition wall 13 that separates the ferrule receiving space formed by the cylindrical portion 11 a of the ferrule receiving portion 11 and the module receiving space formed by the concave portion 12 a of the module receiving portion 12. The partition wall 13 is formed with a hole 13a for passing an optical signal.
In OSA1 using such a sleeve portion 10, in a state where the ferrule 51 of the optical connector 50 is inserted into the ferrule receiving portion 11, an optical signal emitted from the optical fiber 51a of the ferrule 51 is transmitted through the fiber stub 11c. Then, the light passes through the hole 13a and is condensed on the PD 21 by the lens 23a of the optical module 20 included in the module receiving unit 12.

Next, the optical module 20 will be described. The optical module 20 includes, for example, a PD 21, a stem 22, and a lens cap 23.
The PD 21 converts an optical signal into an electrical signal as described above, and is mounted directly or via a submount on an element mounting surface 22c of a base 22a (to be described later) of the stem 22.

The stem 22 cooperates with the lens cap 23 to form a CAN package having an element mounting space therein. The stem 22 has a disk-like base 22a on which the PD 21 and the like are mounted, and is supported by the base 22a. And lead pins 22b for electrical connection.
The base 22a is formed of a resistance weldable material (for example, Kovar) so that it can be joined to the cap shell 23b of the lens cap 23 by resistance welding. In addition to the PD 21, an element such as a transimpedance amplifier that amplifies an electrical signal generated by the PD 21, or a resistor or a capacitor may be mounted on the element mounting surface 22c on the upper surface of the base 22a. These elements are connected to each other or to the base 22a or the lead pin 22b by various connecting means. The lead pin 22b is supported by glass sealing on the base 22a.

The lens cap 23 related to the feature of the present invention functions as a cap that hermetically seals the PD 21 and the like in cooperation with the stem 22, and the light incident from the optical fiber 51 a through the fiber stub 11 c and the like is PD 21. And a cap shell 23b for holding the lens 23a.
The lens 23a is, for example, a ball lens, and is fixed to a hole 23c formed in the center of the flat surface 23c of the cap shell 23b with a sealing glass such as a low melting point glass. The present invention is particularly preferably used for OSA when the refractive index of the material used for the lens 23a is high.

  The cap shell 23b is formed of, for example, a material (such as Kovar) that can be pressed and can be resistance welded. The shape is such that the side surface that is continuous with the flat surface 23c for fixing the lens 23a extends upward from the flat surface 23c with reference to the element mounting surface 22c of the stem 22 (hereinafter referred to as an extended shape). It is called out part). In the OSA 1 according to the present invention, the extended portion 40 as described above is formed in the cap shell 23 b, and the outer peripheral surface of the circumferential portion 40 is included in the outer peripheral surface of the optical module 20, whereby the concave portion 12 a of the module receiving portion 12. And increase the bonding area. The cap shell 23b is hermetically fixed to the stem 22 by resistance welding the lower part thereof and the base 22a of the stem 22.

  The OSA 1 is assembled by bonding and fixing the outer peripheral surface of the cap shell 23 b constituting the outer peripheral surface of the optical module 20 and the inner peripheral surface of the recess 12 a of the module receiving portion 12 of the sleeve portion 10 with an adhesive resin 30. It is done.

  As described above, in OSA1, the upper outer periphery of the cap shell 23b bonded with the adhesive is folded back, and the height of the cap shell 23b with respect to the element mounting surface 22c of the stem 22 is set to be the same with respect to the surface 22c. The extension portion 40 is formed so as to be larger than the position (height) of 23a (the center thereof) so as to earn a wide bonding area. Thereby, the fixing strength (adhesion strength) in OSA1 can be made high, and the reliability can be improved. Further, by making the height of the cap shell 23b larger than the position of the lens 23a, there is a secondary effect that can prevent damage to the lens 23a due to disturbance.

FIG. 2 is a cross-sectional view illustrating an OSA according to another embodiment of the present invention. In the OSA of the present embodiment, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The OSA of FIG. 2 includes a sleeve portion 10 similar to the OSA of FIG. However, the configuration of the optical module 60 is different from that of FIG. Specifically, in the optical module 60, unlike the optical module of FIG. 1, a lens holder 61 having a cup-shaped cap shell 61a is fixed to the stem 22, and a ring-shaped member is formed around the cup-shaped member of the cap shell 61a. A ring member (cylindrical member) 62 is fixed.

  The cap shell 61a of the optical module 60 is formed of, for example, a material that can be pressed and can be resistance-welded (such as Kovar). A hole 61b for fixing the lens 23a is formed at the center of the plane. The cap shell 61 a is hermetically fixed to the stem 22 by resistance welding the lower portion thereof and the base 22 a of the stem 22.

  The ring member 62 is formed by cutting out from a pipe-shaped metal member, and is fixed to the outer periphery of the cap shell 61a by fitting. The side surface of the ring member 62 constitutes the side surface of the optical module 60. In the OSA 2, the side surface (outer peripheral surface) of the ring member 62 as the side surface of the optical module 60 and the inner peripheral surface of the recess 12 a of the module receiving portion 12 of the sleeve portion 10 are bonded and fixed by an adhesive resin 30. It is done.

  Further, the height of the ring member 62 is substantially the same as or higher than the height of the center of the lens 23 a with respect to the element mounting surface 22 c of the stem 22. That is, the axial dimension is larger than the height of the cap shell 61a. By fixing the ring member 62 to the outer periphery of the cap shell 61a, the optical module 60 has a side surface height with respect to the element mounting surface 22c of the stem 22 as well as the center of the lens 23a (with respect to the surface 22c). ) Position (height). In other words, in the optical module 60, the extending portion 40 that is a feature of the present invention is formed by fixing the ring member 62 described above to the cap shell 61a.

  As described above, in the OSA 2, the extended portion 40 is formed by the ring member 62 so as to earn a wide bonding area. Thereby, the fixing strength of OSA2 can be made high and the reliability can be improved.

It is a figure explaining the outline of OSA concerning one embodiment of the present invention. It is a figure explaining the outline of OSA which concerns on other embodiment of this invention. It is a figure explaining the outline of the conventional OSA. It is a figure explaining the outline of the conventional OSA.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Optical subassembly (OSA), 10 ... Sleeve part, 11 ... Ferrule receiving part, 11a ... Cylindrical part, 11b ... Opening, 11c ... Fiber stub, 12 ... Module receiving part, 12a ... Recessed part, 13 ... Partition wall, 13a ... hole, 20 ... optical module, 21 ... photoelectric conversion element (PD), 22 ... stem, 22a ... base, 22b ... lead pin, 22c ... element mounting surface, 23 ... lens cap, 23a ... lens, 23b ... cap Shell, 23c ... plane, 23d ... hole, 30 ... adhesive resin, 40 ... extension, 50 ... optical connector, 51 ... ferrule, 51a ... optical fiber, 60 ... optical module, 61 ... lens holder, 61a ... cap shell, 62: Ring member.

Claims (3)

A coaxial optical module in which a cap shell formed by press processing for holding a condensing lens is mounted on a stem on which a photoelectric conversion element is mounted, and a sleeve member for aligning ferrules of the optical connector,
The cylindrical outer peripheral portion of the cap shell is provided with an extending portion that extends upward from the lens holding surface of the cap shell,
The sleeve member is formed with a recess for storing the cap shell,
An optical subassembly comprising: an outer peripheral surface of the coaxial optical module including an outer peripheral surface of the extending portion provided in the cap shell; and an inner peripheral surface of a concave portion of the sleeve member fixed by an adhesive. .   The optical subassembly according to claim 1, wherein the extension portion is formed by folding an upper outer periphery of the cap shell.   The extension portion is formed by fitting and fixing a cylindrical member having an axial dimension larger than the height of the cap shell to an outer peripheral portion of the cap shell. Optical subassembly.

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